The BBC's worldwide reputation for accuracy took a blow yesterday after it broadcast an interview with a hoaxer who claimed to offer a $12bn settlement to the 120,000 surviving victims of the Bhopal disaster.

Hopes were raised in India when the BBC's international news channel, BBC World, interviewed a man identified as a representative of Dow Chemical, which now runs the Bhopal plant after taking over Union Carbide.

He said Dow accepted full responsibility for the world's worst industrial disaster, which has claimed the lives of 20,000 people over the past 20 years, and left many more with chronic health problems.

But it soon emerged that Jude Finisterra was a hoaxer who has targeted Dow Chemical in the past. His interview, which was picked up and reported internationally, was shown twice on BBC World, and on BBC television and radio in Britain, before it was pulled.

"Today I am very, very happy to announce that today, for the first time Dow is accepting full responsibility for the Bhopal catastrophe. This is a momentous occasion," he said in the live interview. In public, the BBC said it had moved "swiftly" to correct the mistake and stressed it had been the victim of an "elaborate" hoax.

It condemned the actions of Mr Finisterra as a "tasteless publicity stunt". But in private, some BBC journalists expressed surprise that the hoax was not identified more quickly: the apology seemed extraordinary because Dow maintains that it has "no responsibility" for Bhopal.

The corporation said a producer on BBC World had been asked to book a representative from Dow for the 20th anniversary of the disaster. He went to the Dow website, and was directed to the media relations section. Email correspondence and phone calls followed, which resulted in yesterday's interview with Mr Finisterra from the corporation's Paris office.

It appears that part of the Dow website had been hijacked in a detailed and carefully planned operation.

The corporation was keen to stress that it was the victim of a stunt. It said in a statement: "This interview was inaccurate, part of an elaborate deception. The person did not represent the company and we want to make clear that the information he gave was entirely inaccurate." Dow confirmed that Mr Finisterra did not work for the company.

The incident raises the issue of internet security, and the BBC said its procedures regarding the trustworthiness of information obtained from websites would be reviewed.

Mr Finisterra later told The World at One on Radio 4 that he was part of Yes Men group, which hoaxes businesses and governments."I was speaking on behalf of Dow in a certain way. I was expressing what they should express."

He added that he had heard Bhopal residents had broken down in tears when they learned of the report, and he felt bad about it.